The field of the invention relates to generally to electronic devices having openings in their housings through which radio frequency energy can escape. More particularly, the present invention relates to electronic devices having CD/DVD drives, extension cards, or other internal components that are insertable and removable by users.
Radio Frequency (RF) energy emitted by electrical components can interfere with the operation of radios, computers, televisions, and other electrical equipment. Consequently, efforts are made to shield sources of RF energy and restrict stray RF energy to confined areas, such as within the housing of an electronic device. It is difficult however, to contain RF energy for two reasons. First, RF energy can pass unimpeded through non-electrically conductive materials such as nylon, felt, and plastic. Second, RF energy can escape through tiny, thin openings in shielding materials that are greater than {fraction (1/20)}th of the RF energy""s wavelength. With today""s computer processors approaching the 1 GHz range and beyond, the size of the minimally allowable gaps in shielding shrinks to about 2-3 mm long.
Where most electrical devices are concerned, the problem is not in shielding the housing of the electrical device, but in shielding openings in the housing, particularly those openings through which objects such as CD""s and DVD""s are inserted and removed. In the past, openings in the housing were shielded in two ways. First, the openings were equipped with a dust cover, typically nylon or plastic bristles intertwined to form a mesh slot, to reduce the amount of dust or other contaminants entering the interior of the housing. Second, the loading bay doors were shielded with a material impermeable to RF, which formed an RF blocking seal when the doors were closed.
These efforts, however, proved unsatisfactory for several reasons. First, the dust covers were not made of materials impermeable to RF energy. Additionally, prior art dust covers often had sizable gaps along the length of the dust cover slot. Consequently, RF energy escaped from the housing each time the loading bay doors were opened to allow insertion or removal of a CD, DVD, or other device. Second, dust covers made of abrasive materials, such as nylon and plastic, could scratch the surfaces of CD""s and DVD""s, thereby impairing their playability over time. Clearly, a solution is needed that contains RF energy whenever the main RF seal (loading bay door) is broken.
Particularly, as the shortcomings of the prior art show, it is desirable to provide a non-abrasive means to shield the openings in the housings of electronic devices such that RF energy is contained within the housing whenever the main RF seal (loading bay door) is broken. It is particularly desirable that such means of blocking RF energy permit the insertion and removal of objects such as CD""s and DVD""s.
As shown in the accompanying Figures and as described below, the present invention provides such a solution.
An apparatus and methods to contain radio frequency energy within the housing of an electronic device are provided. The apparatus includes a flexible covering attached to the housing of the electronic device to cover an opening in the housing. The flexible covering is substantially impermeable to radio frequency energy and has a slot formed therein to allow objects to be inserted into and removed from the interior of the electronic device. In one embodiment, the flexible covering is an electrically conductive cloth. The cloth may be supported by a frame and attached to the housing, or be simply attached to the housing, using an electrically conductive adhesive. The edges of the slot are substantially coterminous along the length of the slot to trap radio frequency energy within the housing of the electronic device. A colored dust cover may be attached to the flexible material to provide a desired aesthetic appearance.